When you tame a rune beetle, if a skill is GM or below, 100 is the cap.
This is true, however the second half of your statement is incorrect.
Any skills above GM will cap at the level they are when you tame the beetle. They won't go above that, and if they die they can be retrained to that cap.
According to my data, when a Rune Beetle is tamed, any spawned skill above 100.0 will cap out at 90% Spawned Value (if the this ends up being less than 100.0, than 100.0 is the skill cap). According to the Hunter's Guide, the Rune Beetle has the maximum spawned skills of:
Wrestling: 80.0
Tactics: 95.0
Resist Spells: 110.0
Anatomy: 0.0
Poisoning: 140.0
Magery: 110.0
Eval Int: 125.0
Meditation: 110.0
For
Resist Spells,
Magery, and
Meditation If you calculate 90% of 110.0 it yields 99.0 (=0.9*110.0), so those skills can only be trained to 100.0.
For
Poisoning and
Eval Int are the only skills which can be greater than GM for a Tamed Rune Beetle (max tamed Eval Int = 112.5; max tamed Poisoning = 126.0).
You are correct in that they can be retrained to their new skill maximums to recover rom skill loss incurred upon death.
Stayin Alive,
BG
Reference Rune Beetle Hunter's Guide:
http://uo.stratics.com/database/view.php?db_content=hunters&id=1449